Although the technical advance of an engine is indispensable as a background for supporting the development of an automobile industry, recently, regulations on exhaust emissions, which is made tighter than ever due to the effect of environmental problems, cause the automobile manufacturers of the respective countries to shift to design an engine for coping with a more strict regulation for environmental pollution.
At present, an engine control technology in the main stream is an ECU (Engine Control Unit or Electric Control Unit). The ECU is of a microcomputer which precisely controles an amount of injected fuel, a timing of fuel injection, a timing of ignition, and the like, based on the information detected by sensors disposed around an engine so that the engine can be kept in an optimum condition.
An exhaust gas regulation requires the ECU to optimize the engine not only from a view point of a generated torque but also from a view point of exhaust gas. Moreover, in some countries it has been determined to measure exhaust gas by minutely determining complex time series patterns and vehicle speeds during the analysis of exhaust gas, and the exhaust gas analysis includes a wide variety of items as to many parameters.
Accordingly, the ECU must determine a correlation among signals obtained from many sensors and reflect the correlation to an engine control.
Heretofore, it has been attempted to determine a correlation by measuring the many signals and displaying them on the same screen (refer to, for example, patent document 1).
In this case, however, technical problems described below arise.
Patent document 1: Japanese Patent Laid-open Publication No. 9-170967